S U M M A R Y This paper describes a method in which vertical resistivity sections are generated tomographically from measurements on a linear array of equally spaced electrodes inserted a t the ground surface. T h e array is multiplexed t o a resistivity meter which gathers one set of all possible independent apparent resistivity measurements and the geophysical section is then reconstructed by backprojecting these weighted data, along equipotentials, into t h e subsurface. T h e technique has been evaluated numerically a n d in field trials over shallow archaeological structures at Fountains Abbey.